This invention relates to vehicles and more particularly to a method of and components for the grounding of vehicle electrical systems in a manner especially suitable for use in over the highway trucks and tractors.
An over the highway truck or tractor is typically equipped with a frame that includes two elongate frame rails. In manufacture, a formed frame rail is moved along an assembly line where it is heat treated and cleaned. The rail stops for a brief period to have a serial number manually applied by a programmed engraving machine. Thereafter, a powder coat material is applied to the rail before the rail enters an oven heated to a temperature of 400xc2x0 F. to 450xc2x0 F. When the frame and the material are heated sufficiently, the powder is cured into a protective coating in a process which consumes from about 45 minutes to about an hour.
As a step in the manufacture of a motor vehicle, a small area of the cured protective coating is removed from the frame by grinding to provide a location for attachment of a ground in the form of an end weldable stud. Under current practice, the location of the end weldable stud is manually determined. Errors in determining that location can result in the stud being positioned at a location which interferes with subsequent assembly of the vehicle. In addition, the studwelding operation is time consuming and expensive. It also creates a house cleaning problem in that each stud is surrounded by a ceramic insulator during the end welding operation. The ceramic insulator is broken away and typically the parts of it are allowed simply to fall to the floor below.
Accordingly, it would be desirable to provide a system for connecting a ground cable to a frame which eliminates the use of end weldable studs and its expense and problems.
With the present invention, a hole for a ground cable fastener is precision punched at the time when the frame is prepunched for other apertures. When the frame moving along a processing line pauses for the application of a serial number, steps of the novel process are also performed. These steps include applying a solder paste to the rail in an annular area around the prepunched grounding hole. Such an application may be on one surface or opposed surfaces of the frame rail. A locating and retaining projection of a mask is then inserted into the grounding hole to position an annular mask over the applied solder paste. Subsequently, the powder coating is applied and the frame is transported to a heated oven as in the prior art. During the heating of the frame in the oven, the paste forms a plated solder ring in the annular area to which the paste was applied. The ring is formed concurrently as the protective powder is fused into a protective coating. After the solder ring is formed the mask is removed.
The mask removal is done preferably as the frame is assembled into a vehicle. During the assembly a ground cable is brought into electrically conductive physical contact with the plated ring by a fastener extending through a cable contact and the hole around which the plated contact has been formed.
The preferred paste is a finely ground mixture of 50xe2x80x9450 tin and lead combined with applicable flux. A commercially available paste which tests have shown to be appropriate for the purpose is sold by Bow Electronic of Syreville, New Jersey. Bow Electronic makes the flux available for application by a dispenser in the nature of a caulking or cookie gun which is adapted to dispense the material through a multi-orficed or nozzle applicator to form annular rings. Alternatively, the paste can be applied by techniques such as use of a brush.
The advantages include reduced time for manufacture because all steps are preformed concurrently with other manufacturing steps. Other advantages include elimination of the steps of measuring to determine a location for a weld stud to be located and preparation of the frame for the application of the weld stud as well as the application of the weld stud itself. The ultimate weight of the vehicle is reduced slightly, which is vital to over the highway haulers. In addition, labor on a moving truck assembly line is reduced and a part number is eliminated.
Another important factor is, one eliminates the corrosion which occurs around the frame weld at the stud location and at a non-plated weld end shoulder of the stud. Obviously, there are additional savings in electricity, maintenance, labor and need for ceramic insulators as well as weld studs, plus the housekeeping improvements occasioned by the lack of insulator pieces after the insulators are broken.
For service and repair one simply needs to clean a desired area to bare metal, apply the paste and heat it with any suitable heat source such as a propane torch.
Accordingly, the objects of the invention are to provide a novel and improved method and apparatus for effecting ground connections in motor vehicles.